The invention relates to a novel process for the production of oligomeric and polymeric telechelic substances, to the telechelic substances produced in this manner and to the use thereof in the plastics, fibers or lacquer sectors.
Telechelic substances are generally defined as linear oligomers or low molecular weight linear polymers having functional groups on both chain ends. A comprehensive review of the production of telechelic substances may be found, for example, in Adv. Polym. Sci. 81, 168 (1987). They are significant, inter alia, as additives and as structural units (prepolymers) for copolymers having a defined structure (e.g., block copolymers, comb polymers, star polymers). When used as structural units in copolymers, telechelic substances must be as precisely bifunctional as possible.
The best known reactions for the production of telechelic substances which have a functionality of exactly two are (1) polyaddition reactions (for example, to yield polyurethanes or polyureas), (2) polycondensation reactions (for example, to yield polyesters, polycarbonates, or polyamides) as well as (3) ring-opening anionic or cationic polymerization reactions of heterocyclic monomers (for example, cyclic esters, carbonates, acetals or ethers), optionally with terminating reagents containing the desired functional groups.
Telechelic polyacrylates, i.e. low molecular weight acrylate polymers having two defined functional end groups which can participate in crosslinking, chain extension and/or coupling reactions conventionally used in lacquer chemistry are of great interest for use in the lacquer industry Telechelic polyacrylates, however, cannot be produced using any of the above-stated processes.
Various methods are known in polymer chemistry for incorporating functional end groups into polyvinyl or polyacrylate compounds, for example, oxidative chain scission (e.g., with oxygen, ozone, osmium or ruthenium tetroxide). However, these methods are non-specific and/or require the presence of double bonds in the polymer chains as a point of attack for scission. It is virtually impossible to achieve exact bifunctionality with these methods.
If monomers having the desired functional group are used in a free-radical polymerization in a quantity calculated to yield a functionality of two, a product mixture is obtained having an average functionality of two. The product, however, contains not only bifunctional molecules, but also tri- and more highly functional molecules, monofunctional molecules as well as non-functional polymer molecules.
If initiators and/or terminating reagents having the desired functional groups (such as functionalized diazo compounds, functionalized peroxides or redox initiators) are used instead of the monomers having functional groups, a functionality of two is generally not achieved because various termination reactions co-occur, e.g. disproportionation, recombination, termination by initiator radicals or termination by the terminating reagent.
In xe2x80x9cdead andxe2x80x9d polymerization, a large excess of an initiator having the desired end group is used. In this technique, each polymer chain can be terminated with an initiator molecule and is accordingly bifunctional. However, only very low molecular weight polymers are formed and large quantities of initiator are required.
Telomerization (i.e., polymerization of vinyl or arcrylate monomers in the presence of chain-transfer reagents having elevated chain-transfer constants) also yields only low molecular weights and this method is restricted to a few instances (e.g., Polymerization in the presence of tetrachloromethane, dibromomethane or disulfides having functional groups). since it is not entirely possible to suppress disproportionation as a termination reaction between two active chain ends, telechelic substances are obtained having functionalities of less than two. At least in the case of the halogen compounds, it is also necessary to perform a subsequent polymer-analogous reaction of the halogen substituents to yield the desired functional groups.
Telechelic polymethacrylates may be produced by group transfer polymerization with ketene silyl acetals, wherein the functional groups are formed by transformation of the silyl groups. Disadvantages of this method are (1) the requirement of high purity monomers and solvents and (2) the price and availability of the initiators which are needed, requirements which make such a process useful only for special applications.
EP-A 613,910 and EP-A 622,378 disclose the production of xcex1-xcfx89-polymethacrylate diols by selective transesterification of the terminal ester group of an xcex1-hydroxy-functional polyalkyl methacrylate. This process has various disadvantages. First, the xcex1-hydroxy-functional polyalkyl methacrylate is produced by free-radical polymerization in the presence of large quantities of mercaptoethanol, a compound which has a considerable odor nuisance. Second, the method is a multi-stage, energy-intensive and time-consuming process; the process involves the removal of the excess mercaptoethanol and the solvent used by distillation, transesterification with an excess of a diol in the presence of a catalyst, removal of the methanol by distillation, repeated washing of the product to remove the catalyst and excess diol as well as still further purification stages. Third, this reaction is restricted solely to the use of alkyl methacrylates, since the transesterification reaction otherwise no longer proceeds sufficiently selectively on the terminal ester group of the chain.
Another special technique which has a limited range of applications and no economic potential is ring-opening polymerization of unsaturated heterocyclics (for example, cyclic ketene acetals, unsaturated spiroorthocarbonates); such monomers are not industrialy avilable.
None of the methods so far mentioned is thus suitable for the production of the desired telechelic polyacrylates, because the desired functionality is not achieved, the method is restricted to only a few specific cases and/or polymer-analogous subsequent reactions are required. There is a need for a polymerization process which combines ease of performance with good control of the polymerization and in particular of the end groups of the polymer chains. Living free-radical polymerization is one such process.
Living free-radical polymerization is a relatively recent method for the performance of controlled free-radical polymerization. It combines the advantages of conventional free-radical polymerization (simple production process, low costs and a wide range of monomers) with those of living polymerization (polymers of a defined structure, molecular weight, molecular weight distribution and end group functionality). In this process, the objective of precise control of the free-radical polymerization is achieved by reversible chain termination/blocking (xe2x80x9cend-cappingxe2x80x9d) after each growth stage. The equilibrium concentration of the actively polymerizing chain ends at this point is so low in comparison with the equilibrium concentration of the blocked (xe2x80x9cdormantxe2x80x9d) chain ends that termination and transfer reactions are largely suppressed in comparison with the growth reaction. since the end-capping is reversible, all the chain ends remain xe2x80x9clivingxe2x80x9d providing that no terminating reagent is present. This allows control of the molecular weight, a narrow molecular weight distribution and purposeful functionalization of the chain end by terminatig reagents.
Initial attempts at controlled free-radical polymerization (using the iniferter method) were described, for example, in Makromol. Chem., Rapid Commun. 3 (1982), 127 and 132. The iniferter method here describes a class of free-radical initiators which can enter into initiation, transfer and reversible termination reactions, e.g., tetraalkylthiuram disulfides which are photolytically cleaved and activated. In this manner, it is possible to produce polymers having dithiocarbamate end groups and which may be reactivated by irradiation.
U.S. Pat. 4,581,429 discloses the principle of reversible chain termination by using free-radicals based in linear or cyclic nitroxides such as tetramethyl-1-piperidinyloxy (TEMPO). If this nitroxide is reacted with a reactive carbon radical capable of initiating a free-radical vinyl polymerization reaction, a reversibly cleavable Cxe2x80x94O bond is formed which, when subjected to moderate heating, is capable of bringing about polymerization by insertion of vinyl monomers between the nitroxide and carbon radical. After each monomer addition, the newly formed radical is xe2x80x9cscavengedxe2x80x9d by the nitroxide; this reversibly blocked chain end may then insert further monomer molecules. Functional end groups are also described and in this case are obtained by polymer-analogous.
This concept of reversible termination with nitroxide has been developed into a practical polymerization method in, for example, J. Am. Chem. Soc. 116, 11185 (1994), Macromolecules 28, 2993 (1995), U.S. Pat. Nos. 5,322,912, 5,401,804, 5,412,047 and 5,449,724; and WO 94/11412, WO 95/26987 and WO 95/31484. The starter system used in this case is a combination of dibenzoyl peroxide (BPO) and TEMPO.
Another approach is Atom Transfer Radial Polymerization (ATRP), in which a transition metal complex compoundd MLx abstracts a transferable atom or group of atoms X (for example, Cl and Br) from an organic compound RX to form an oxidized complex compound MLxX and an organic radical Rxe2x80xa2, which undergoes an addition reaction with a vinyl monomer Y to form the carbon radical RYxe2x80xa2. This radical is capable of reacting with the oxidized complex compound, transferring X to RYX and MLx, which can initiatae a new ATRP reaction and thus a further growth stage. The actively polymerizing species RYxe2x80xa2 is thus reversibly blocked by the abstractable group x with the assistance of the transition metal compound, which makes the redox process possible (for example, Macromolecules 28, 1721 (1995); Macromolecules 29, 1070 (1996), Macromolecules 28, 7970 (1995), WO 95/25765, WO 96/30421 and WO 97/18247).
It is an object of the invention to provide a process that produces a homo- or copolymer having a purposefully established molecular weight and narrow molecular weight distribution in a single reaction stage from one or more vinyl monomers, in particular, acrylate monomers and styrene.
It is an object of the invention to provide a process in which the resultant polymers have two functional end groups which are capable of further reaction or crosslinking with the functional groups usual in lacquer chemistry.
The foregoing objects have been achieved by a process in which telechelic substances may purposefully be produced by free-radical (co)polymerization of olefinically unsaturated monomers using the living free-radical polymerization method with an initiator system, which optionally contains one of the desired functional groups, in the presence of a functionalizing reagent, which has the desired functional group and terminates the chains once the monomers have been consumed.
The present invention relates to a process for the production of oligomeric and polymeric telechelic substances of the formula
Y1xe2x80x94Qxe2x80x94Y2 
wherein
Q represents an oligomeric, optionally substitued hydrocarbon residue with a molecular weight 300 less than Q less than 10000 of the formula 
in which n is an interger in the range 3xe2x89xa6nxe2x89xa6500 and Rxe2x80x2, Rxe2x80x3, Rxe2x80x2xe2x80x3 may mutually independently be H, C1-C20-(cyclo)alkyl, C6-C24-aryl, Halogen, CN, C1-C20-alkyl ester oder alkylamide, C6-C24 arylester or arylamide, wherein Rxe2x80x2, Rxe2x80x3, Rxe2x80x2xe2x80x3 may also contain further functional groups such as, for exemple, aldehyde, keto or ether groups and Rxe2x80x2 and Rxe2x80x3 may also be constituents of a ring, for example, in a cyclic anhydride, cyclic imide or cyclic alkane and the functional gropus Y1, Y2 may be identical or different. the process involves the polymerization of:
A) free-radically polymerizable, ethylenically unsaturated monomers of the formula
Rxe2x80x2HCxe2x95x90CRxe2x80x3Rxe2x80x2xe2x80x3, 
xe2x80x83in which Rxe2x80x2, Rxe2x80x3, Rxe2x80x2xe2x80x3 have the above-stated meaning and contain none of the functional groups Y1, Y2, or a mixture of such monomers with
B) an initiator compound or a mixture of such compounds,
C) a transition metal compound or a mixture of compound and
D) one or more complex ligands which are capable of complexing the central atom(s) of the compound C, characterized in that polymerization is performed
E) a functionalizing reagent which has at least one Cxe2x95x90C double bond and least one of the desired functional groups Y1, Y2.
The present invention also provides the telechelic substances obtainable using the process according to the invention.
The present invention also provides the use of the telechelic substances according to the invention as structural units for plastics, adhesives or fibers and as a binder, binder component or structural unit for binder components in coating compositions and adhesives.
A preferred process is for the production of oligomeric or polymeric telechelic substances Y1xe2x80x94Qxe2x80x94Y2 of the molecular weight 500 less than Mn less than 10000, in which Q denotes an oligomeric or polymeric, optionally substituted, hydrocarbon residue as defined above with a molecular weight 300 less than Q less than 10000 and Y1, Y2 may be identical or different and represent functional groups reactive towards isocyanates, alcohols, carboxylic acids or epoxides, by polymerization of
A) free-radically polymerizable, ethylenically unsaturated monomers of the formula
Rxe2x80x2HCxe2x95x90CRxe2x80x3Rxe2x80x2xe2x80x3, 
xe2x80x83in which Rxe2x80x2, Rxe2x80x3, Rxe2x80x2xe2x80x3 have the above-stated meaning and contain none of the functional groups Y1, Y2, or a mixture of such monomers, which contain no groups Y1, Y2 in the molecule, or a mixture of such monomers with
B) an initiator compound R1R2R3Cxe2x80x94X, which contains one or more free-radically abstractable or transferable atoms or groups of atoms X, in which R1 represents either X or a linear or branched alkyl residue which is substituted either with X or with Y1 and, optionally, further residues, and R2, R3 mutually independently represent hydrogen or optionally substituted, linear or branched aliphatic or aromatic hydrocarbon residues or electron-attracting substituents such as COOR, CN, NO2, COCl, CONHR, CONR2, or COR,
C) a transition metal compound MpZq, which is prepared from a cation of a metal M from the group comprising cu, Fe, ru, Cr. MO, Wo, Mn, Rh, Re, Co, Ni, V, ZN, Au, Ag or Sm, wherein M may be present in the transition metal compound in different oxidation states and may participate in a reversible redox process, and an anion Z from the group comprising halide, hydroxide, C1-C6 alkoxy, SO42xe2x88x92, PO42xe2x88x92, R4PO42xe2x88x92, R4R5PO4xe2x88x92, R3R4R5Pxe2x80x94, CF3COOxe2x80x94, PF6xe2x88x92, CH3SO3xe2x88x92, ArSO3xe2x88x92, CNxe2x88x92 oder R4COOxe2x88x92, wherein R4, R5 mutually independently represent hydrogen or an optionally aryl- or halosubstituted alkyl residue, and wherein p and q are determined by the valencies of M and Z in the transition metal compound and
D) a mono- or polydentate complex ligand L, which contains one or more nitrogen, oxygen, sulphur or phosphorus atoms and may combine with at least one cation of the metal M to form complexes, characterized in that components A) to D) are reacted in a living free-radical polymerization reaction to yield the telechelic substance Y1xe2x80x94Qxe2x80x94Y2 in the presence of
E) a compound R6R7Cxe2x95x90CR8(R9xe2x80x94Y2), which contains at least one olefinic double bond and at least one functional group Y2 reactive towards isocyanates, alcohols, carboxylic acids or epoxides, wherein a carbon residue R9 must be present between the double bond and Y2, which carbon residue R9 represents a linear or branched, optionally substituted alkyl chain having a minimum length of 1 methylene group, and wherein R6, R7 and R8 mutually independently represent hydrogen or an optionally aryl- or halosubstituted alkyl residue.
Any known free-radically polymerizable olefins and substituted olefins may in principle be used in the free-radically polymerizable, ethylenically unsaturated monomers A. Substituents which may be considered are, for example, hydrogen (H), linear or branched alkyl residues (R) having 1 to 20 carbon atoms, which may optionally also have further substituents, xcex1,xcex2-unsaturated linear or branched alkenyl or alkynyl residues, which may optionally also have further substituents, cycloalkyl residues, which may also have heteroatoms, such as, O, N or S in the ring and optionally further substituents, optionally substituted aryl or heteroaryl residues, halogen, CN, CF3, COOR, CONHR, CONR2, COR (where R=C1-C20).
The free-radically polymerizable double bond of the ethylenically unsaturated monomers A may also be part of a ring such as in cyclic olefins or olefinically unsaturated anhydrides or imides.
Preferably used monomers for the production of Q comprise: (meth)arylic acid esters of C1-C20 alcohols, acrylonitrile, cyanoacrylic acid esters of C1-C20 alcohols, maleic acid diesters of C1-C6 alcohols, maleic anhydride, vinylpyridines, vinyl(alkylpyrroles), vinyloxazoles, vinyloxazolines, vinylthiazoles, vinylimidazoles, vinylpyrimidines, vinyl ketones, styrene or styrene derivates, which have in a xcex1 position a C1-c6 alkyl residue or halogen and have up to three further substituents on the aromatic ring.
Butyl acrylate, 2-ethylhexyl arcylate, methyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, maleic anhydride or styrene are preferably used.
The initiator compound B comprises substances of the formula R1R2R3X containing one or more free-radically abstractable or transferable atoms or groups of atoms X, in which R1 represents either X or a linear or branched C1-c20 alkyl residue, which is substituted either with X or with Y1 and optionally further residues and R2, R3 mutually independently represent hydrogen or optionally substituted, linear or branched C1-C20 aliphatic or C6-c24 aromatic hydrocarbon residues or electron-attracting substituents such as, for example, COOR, CN, NO2, COCl, CONHR, CONR2 or COR (where Rxe2x95x90C1-C20). Compound B may either B1) contain a functional group Y1 or B2) contain no Y1, but instead contain in the substituents an additional group X (i.e., a total of two groups X per initiator molecule).
In the initiator compounds B1, the residue R1 may be described by the formula Y1xe2x80x94R10, in which R10 represents a linear or branched hydrocarbon residue with 1-10 carbon atoms and optionally substituted with aromatic residues, which hydrocarbon residue may optionally also contain ether, ester, amide, urethane or urea gropus and may additionally also contain linear polymeric blocks such as polyether blocks, polyester blocks or polyacrylate blocks, and Y1 represents a functional group selected from xe2x80x94OH, xe2x80x94Cl, xe2x80x94COOH, xe2x80x94COOR, xe2x80x94CN, xe2x80x94NO2, xe2x80x94SO3H, xe2x80x94COCl, xe2x80x94CONHR, xe2x80x94CONR2, xe2x80x94OR, xe2x80x94OP(xe2x95x90O)R, xe2x80x94OP(xe2x95x90O)(OR), xe2x80x94OP(xe2x95x90O)(OR)2 or xe2x80x94C(xe2x95x90O)R and R, R1, R2 and R3 have the above-stated meaning.
Compounds of the formulae 
are preferably used as component B1, wherein Halxe2x95x90Cl or Br, R13=C1-C6 alkyl, R14=H or CH3, n=1-10 and m=1-225.
In initiator compounds B2 residue R1 may be identical to X or be described by the formula Xxe2x80x94CR10R11R12, in which R2, R3 and R10 have the above-stated meaning and R11 and R12 mutually independently represent hydrogen or optionally substituted, linear or branched aliphatic or aromatic hydrocarbon residues. Compounds of the formulae 
are preferably used as component B2, wherein Halxe2x95x90Cl or Br, R13=C1-C6 alkyl, R14=H or CH3, n=1-225 and m=2-6.
The transition metal compound C comprises substances of the formula MpZq, which are prepared from a cation of a metal M from the group comprising Cu, Fe, Ru, Cr, Mo, Wo, Mn, Rh, Re, Co, Ni, V, Zn, Au, Ag or Sm, wherein M may be present in the transition metal compound in different oxidation states and may participate in a reversible redox process, and an anion Z from the group comprising halide, hydroxide, C1-C6 alkoxy, SO42xe2x88x92, PO43xe2x88x92, R4PO42xe2x88x92, R4R5PO4xe2x88x92, R3R4R5Pxe2x80x94, CF3COOxe2x80x94, PF6xe2x88x92, CH3SO3xe2x88x92, ArSO3xe2x88x92, CNxe2x88x92 oder R4COOxe2x88x92, wherein R4, R5 mutually independently represent hydrogen or an optionally C6-C24 aryl- or halo-substituted (Cl. Br) alkyl residue, and wherein p and q denote a number of 1, 2, 3, 4 or 5 and are not determined by the valencies of M and Z in the transition metal compound. CuCl, mixtures of CuCl and CuCl2, CuBr or mixtures of CuBr and CuBr2 are preferably used as component C.
The anion Z of the transition metal compound is conventionally the same as the abstractable group X of the initiator. Z and X may, however, also be different.
Component D comprises one or more complex ligands L, which may be mono- or polydentate, which contain one or more nitrogen, oxygen, phosphorus or sulfur atoms and may combine with at least one cation of the metal M to form complexes. Examples of such ligands are diamines, diamides, aminoalcohols, diols, hydroxycarboxylic acid esters, aminocarboxylic acid esters, bipyridines, bipyrroles, phenanthrolines, cryptands, crown ethers or porphyrins. Ligands which complex the central atom (for example by means of xcfx80 bonds), aromatic compounds, (poly)olefins or (poly)alkynes, as well as cyclopentadienyl compounds may also be suitable. Compounds of the formula 
are, however, preferably used as component D, wherein R15 to R18 mutually independently represent hydrogen or C1-c20 aliphatic or C6-C24 aromatic hydrocarbon residues, and R15 to R18 may optionally also be linked together to form an unsaturated, optionally aromatic, ring containing nitrogen, and wherein component D may also be attached to a polymer or incorporated into a polymer chain by means of one or more of residues R15 to R18.
It is essential to the invention that polymerization is performed in the presence of a functionalizing reagent E. This reagent comprises a compound of the formula R6R7Cxe2x95x90CR8(R9xe2x80x94Y2), which contains at least one olefinic double bond and at least one functional group Y2 reactive towards isocyanates, alcohols, carboxylic acids or epoxides, wherein a carbon residue R9 must be present between the double bond and Y2, which carbon residue R9 represents a linear or branched, optionally substituted C1-C20 alkyl chain having a minimum length of 1 methylene group, and wherein R6, R7 and R8 mutually independently represent hydrogen or an optionally aryl- or halo-substituted alkyl residue. In some cases a mixture of such compounds may also, but not preferably, be used. Component E is preferably selected from compounds of the group. 
wherein R19 represents hydrogen or a linear or branched C1-C6 alkyl chain and R20 and R21 represent any desired hydrocarbon residues having 1 to 20 C atoms, R22 is hydrogen or a C1-C20 alkyl residue, preferably methyl, n may be 1-4 and m my be 1-10. It is particularly preferred to use 2-propen-1-ol, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol or the propoxylated derivates thereof obtained by addition of 1-10 mol of propylene oxide onto the OH group.
In order to produce the desired telechelic substances using the process according to the invention, components A to E must be present in the system in certain molar ratios. The complex ligand D should be present relative to the transition metal compound C at a molar ratio of D:C of 1:1 to 4:1. preferably of 0.5:1 to 3.1. The initiator compound B must here be present relative to the transition metal compound C at a molar ratio of B:C of 0.3:1 to 5:1, preferably of 1:1 to 3:1. Component E is used in a quantity corresponding to a molar ratio of B:C of 0.3:1 to 5:1, preferably of 1:1 to 3:1. Component E is used in a quantity corresponding to a molar ratio of Cxe2x95x90C double bonds in component E to transferable atoms/groups of atoms X in component B of at least 1:1, preferably of at least 3:1.
The quantity of component A (monomers) to initiator compound C is determined as a function of the desired molecular weight or degree of polymerization of the telechelic substance. Since the process according to the invention involves a living polymerization reaction, from which termination or transfer reactions are substantially absent, and component E does not undergo addition onto the active chain ends until after component A has been consumed, the person skilled in the art may readily calculate the required initiator concentration [B] for a given initial monomer concentration [A0] if a degree of polymerization Pn is to be achieved:
[B]=xpxe2x80xa2[A0]/Pn 
wherein xp=([A0]xe2x88x92[A])/[A0] represents the degree of concersion and [A] the actual monomer concentration at conversion xp. It is evident from the above that telechelic substances of any desired molecular weight may be produced using the process according to the invention. Preferably, however, molecular weights of 500 less than Mn less than 10000, preferably of 100 less than Mn less than 5000, are established. The molecular weight distributions obtained are very narrow and are within the range 1.1 less than Mw/Mn less than 1.5.
The telechelic substances produed using the process according to the invention have functionalities (Y1+Y2) of 1.6 to 2.0, generally, however, of  greater than 1.8 to 2.0, but never of  greater than 2.0. One of the two end groups may also be present in derivatized or protected form, wherein functionalities of 0.8 to 1.0, geneerally of  greater than 0.9 to 1.0, are then obtained.
The reaction in the process according to the invention may be perfomed at temperatures of between room temperature and 180xc2x0 C., preferably of between 80xc2x0 C. and 150xc2x0 C., preferably of between 90xc2x0 C. and 130xc2x0 C. the reaction may be performed both without solvents (in the monomer or monomer mixture) and in an organic solvent known in lacquer technology. It may be performed in air or under a protective gas atmosphere; a protective gas atmosphere (for example nitrogen or argon) is preferably used.
The telechelic substances Y1xe2x80x94Qxe2x80x94Y2 according to the invention may be used as structural units in block copolymers, which are present, for example, in plastics, fibers, adhesives or binders or binder components in coating compositions. Depending upon the chemical nature of the plastics, fibers, adhesives or binders and the functionalities of the other structural units present therein, the functional groups Y1, Y2 of the telechelic substance may be selected such that the synthesis reactions to yield the block copolymer proceed in a straightforward and controlled manner. It is possible by means of the monomer composition of the central block Q of the telechelic substance to introduce properties into the block copolymers produced therefrom, such as rigidity, flexibility, hydrophobicity, hydrophilicity, deliberate incompatibilities or additional functionalities.
Depending upon the functionality Y1, Y2, the telechelic substances according to the invention may also be used in unmodified form as a binder, binder component, curing agent or curing agent component in coating compositions and adhesives.
The invention is further illustrated but is not intended to limited by the following examples in which all parts and percentages are by weight unless otherwise specified.